Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
int main() {
	int h, w; cin >> h >> w;
	string s[55];
	for(int i=0;i<h;i++){
		cin >> s[i];
	}
	int di[4] = {1, 0, -1, 0}, dj[4] = {0, 1, 0, -1};
	int d[55][55];
	int cnt = 0;
	queue<pair<int, int>> q;
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			d[i][j] = 10000;
			if(s[i][j]=='.'){
				cnt++;
			}
		}
	}
	q.push({0, 0});
	d[0][0] = 0;
	while(q.size()){
		auto p = q.front(); q.pop();
		if(p.first==h-1 && p.second==w-1){
			break;
		}
		for(int k=0;k<4;k++){
			int ni = p.first + di[k];
			int nj = p.second + dj[k];
			if(0<=ni && ni<h && 0<=nj && nj<w && s[ni][nj]!='#' && d[ni][nj]==10000){
				q.push({ni, nj});
				d[ni][nj] = d[p.first][p.second]+1;
			}
		}
	}
	if(d[h-1][w-1]==10000){
		cout << -1 << endl;
		return 0;
	}else{
		cout << cnt-d[h-1][w-1]-1 << endl;
	}
	return 0;
}